First, we can click "crtl-g" of "shell" to test whether the noise was removed from the buzzer, turn off all sounds under Linux console(no X11), you can the command:
setterm -blength 0
#alternatively you can change the frequency of the beep to a #very low value：
setterm -bfreq 10
However, under X11(no matter KDE、Gnome、XFCE or others...), you can:
xset b off
Maybe one possible choice of every one "shell" operation, you can turn off some kind of sound:
For Bash:
# has to go into /etc/inputrc or .inputrc # It will not work in a .bashrc file！
set bell-style none
For Tcsh:
# put this into your .tcshrc file
# just tab completion beep off：set matchbeep = never # any beep off：set nobeep = 1
It's done and have to remind you that's just turn off the noise of buzzer, but not all sounds, you can also enjoy the music as usual.